Simplify the expression. $(3p^{4}-6p^{2}-7p)(-7p^{4})$
First use the distributive property. $ 3 p^4 (-7 p^4) - 6 p^2 (-7 p^4) - 7 p (-7 p^4) $ Simplify. $-21p^{8}+42p^{6}+49p^{5}$